The man who built AIG into a global insurance power over 38 years, former CEO Maurice “Hank” Greenberg, says the giant company is in the middle of a crisis.

In a letter to the board – which sacked him in 2005 in the wake of a financial reinsurance scandal – he urged a delay in last week’s AGM despite AIG saying there was no need to postpone the meeting.

Mr Greenberg, who still wields considerable power over AIG through his control of major shareholder CV Starr, says the company’s $US7.8 billion ($8.3 billion) net first-quarter loss is the worst performance in AIG’s 40-year history.

“As AIG’s largest individual shareholder, I am as concerned as millions of other investors as I watch the deterioration of a great company,” he said in the letter, filed with the US Securities and Exchange Commission last week.

Mr Greenberg says several top AIG shareholders have called him expressing their concern about the “persistent and seemingly endless destruction of value at AIG”.

AIG shares fell nearly 5% after news of the letter.

Mr Greenberg says AIG’s poor performance has led to a “complete loss of credibility with the investment community”.

“Over the last 12 months, shareholders of AIG have lost $US80 billion ($85.3 billion) in the aggregate,” he said. “AIG is in crisis.”